[meteorite-list] Mars Rover Curiosity Moves Onward After 'Marias Pass' Studies

[Ron Baalke]

http://www.jpl.nasa.gov/news/news.php?feature=4690

NASA Mars Rover Moves Onward After 'Marias Pass' Studies
Jet Propulsion Laboratory
August 19, 2015

NASA's Curiosity Mars rover is driving toward the southwest after departing 
a region where for several weeks it investigated a geological contact 
zone and rocks that are unexpectedly high in silica and hydrogen content. 
The hydrogen indicates water bound to minerals in the ground.

In this "Marias Pass" region, Curiosity successfully used its drill to 
sample a rock target called "Buckskin" and then used the camera on its 
robotic arm for multiple images to be stitched into a self-portrait at 
the drilling site. The new Curiosity selfie from a dramatically low angle 
is online at:

http://www.jpl.nasa.gov/spaceimages/details.php?id=pia19808

The rover finished activities in Marias Pass on Aug. 12 and headed onward 
up Mount Sharp, the layered mountain it reached in September 2014. In 
drives on Aug. 12, 13, 14 and 18, it progressed 433 feet (132 meters), 
bringing Curiosity's total odometry since its August 2012 landing to 6.9 
miles (11.1 kilometers).

Curiosity is carrying with it some of the sample powder drilled from Buckskin. 
The rover's internal laboratories are analyzing the material. The mission's 
science team members seek to understand why this area bears rocks with 
significantly higher levels of silica and hydrogen than other areas the 
rover has traversed.

Silica, monitored with Curiosity's laser-firing Chemistry and Camera (ChemCam) 
instrument, is a rock-forming chemical containing silicon and oxygen, 
commonly found on Earth as quartz. Hydrogen in the ground beneath the 
rover is monitored by the rover's Dynamic Albedo of Neutrons (DAN) instrument. 
It has been detected at low levels everywhere Curiosity has driven and 
is interpreted as the hydrogen in water molecules or hydroxyl ions bound 
within or absorbed onto minerals in the rocks and soil.

"The ground about 1 meter beneath the rover in this area holds three or 
four times as much water as the ground anywhere else Curiosity has driven 
during its three years on Mars," said DAN Principal Investigator Igor 
Mitrofanov of Space Research Institute, Moscow. DAN first detected the 
unexpectedly high level of hydrogen using its passive mode. Later, the 
rover drove back over the area using DAN in active mode, in which the 
instrument shoots neutrons into the ground and detects those that bounce 
off the subsurface, but preferentially interacting with hydrogen. The 
measurements confirmed hydrated material covered by a thin layer of drier 
material.

Curiosity initially noted the area with high silica and hydrogen on May 
21 while climbing to a site where two types of sedimentary bedrock lie 
in contact with each other. Such contact zones can hold clues about ancient 
changes in environment, from conditions that produced the older rock type 
to conditions that produced the younger one. This contact is the lure 
that led the rover team to choose Marias Pass as a route toward higher 
layers of Mount Sharp. Pale mudstone, like bedrock the mission examined 
for the first several months after reaching Mount Sharp at an area called 
"Pahrump Hills," forms one side of the contact. The overlying side is 
darker, finely bedded sandstone.

Curiosity examined the Marias Pass contact zone closely with instruments 
mounted on its mast and arm. The unusual levels of silica and hydrogen 
in rocks passed during the climb prompted a choice to backtrack to examine 
that area and acquire a drilled sample.

Buckskin was the first rock drilled by Curiosity since an electrical circuit 
in the drill's percussion mechanism exhibited a small, transient short 
circuit in February during transfer of sample powder from the third target 
drilled in the Pahrump Hills area.

"We were pleased to see no repeat of the short circuit during the Buckskin 
drilling and sample transfer," said Steven Lee, deputy project manager 
for Curiosity at NASA's Jet Propulsion Laboratory, Pasadena, California. 
"It could come back, but we have made changes in fault protection to continue 
safely drilling even in the presence of small shorts. We also improved 
drill percuss circuit telemetry to gain more diagnostic information from 
any future occurrences."

Curiosity reached the base of Mount Sharp after two years of fruitfully 
investigating outcrops closer to its landing site and trekking to the 
mountain. The main mission objective now is to examine layers of lower 
Mount Sharp for ancient habitable environments and evidence about how 
early Mars environments evolved from wetter to drier conditions.

JPL, a division of the California Institute of Technology in Pasadena, 
built the rover and manages the project for NASA's Science Mission Directorate 
in Washington. For more information about Curiosity, visit:

http://www.nasa.gov/msl

http://mars.jpl.nasa.gov/msl/

You can follow the mission on Facebook and Twitter at:

http://www.facebook.com/marscuriosity

http://www.twitter.com/marscuriosity


Media Contact

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
guy.webster at jpl.nasa.gov 

Dwayne Brown / Laurie Cantillo
NASA Headquarters, Washington
202-358-1726 / 202-358-1077
dwayne.c.brown at nasa.gov / laura.l.cantillo at nasa.gov 

2015-271